Merge branch 'release/3.1'

Author: John Luo

src/Logging/Logging.Testing/src/Microsoft.Extensions.Logging.Testing.csproj

@@ -18,7 +18,7 @@
   </ItemGroup>
 
   <ItemGroup>
-    <ProjectReference Include="..\..\..\TestingUtils\Microsoft.AspNetCore.Testing\src\Microsoft.AspNetCore.Testing.csproj" />
+    <Reference Include="Microsoft.AspNetCore.Testing" />
     <Reference Include="Microsoft.Extensions.DependencyInjection" />
     <Reference Include="Microsoft.Extensions.Logging.Console" />
     <Reference Include="Microsoft.Extensions.Logging" />